Automatic regulator for furnaces and the like



Aug. 20, 1929. T sTElN '1,725,678

AUTOMATIC REGULATOR FOR FURNACES AND THE LIKE Filed Feb. 10 1925 lvenl'or: Theodor Stein,

Fig?) *b9 H15 Attorneg.

. 30 neyloss,thatiis to Waste with 4the Hue gases 1S made 3S Small- Patented Aug. 20, 1929.

UNITED .STATES THEODOR STEIN,

or EEELIN-FRIEDENA, V'raro COMPANY, A ConronA'rIoN or NEW YORK.

GERMANY, AssIGNon To GENERAL 'ELEC- l Au'roMATIc REGULATOR FON. EUnNAcEs AND THE LIKE.

Application led February 10, 1925, Serial No. 8,217, and in Germany March 7, 1924.

In automatically acting regulating devices,

' such as are ordinarily met with, there are usually involved lprocesses wherein the quantity or magnitude to be controlled', regulated 5 or adjusted, bears a definite relationship to the `quantity whichl acts on the regulator. In such cases, therefore, eachand everypoi sition of the regulator corresponds to'a definite value of the quantityv to be regula-ted.

- 1 0 However, there exists-processes wherein such. deiniteness ,of relationshipbetween the quantity or magnitude to be controlled and the quantity'whlch acts on the' regulator does not obtain and my invention is directed es pecially to this type of process. A process-of this latter type and oneto which my invention is well adapted 1sthat met with in firing a furnace' such`as theI .furnace of a steam boiler, wheremthe sup-' ply of air .and fuel to the furnace is automatically controlled.l Ina mechanical furnace stoker -which is to work automatically, it is necessary, on/the one hand, to regulate the fuel supply in conformity with the load,

25 while, on the 'other hand, the supply of air .for combustion must be. regulated 1n accord? ance withv the fuel supply, the relatlonshlp between the quantity of anandthe quantity of. fliel having' to be 'chosen sothatthe'chim-v the amount of energy going aspossiblef If the excess of air over and above the quantity theoretically required' for combustion is-too small, yit is well known that the chimney loss grows because with the .flue gases there escapes an unduly large quantity of fuel Eortions that have not been burned up ata or only imperfectly so.

is consumed anunduly large amount of.. the

heat developed, and this passes intothe waste or-'fiue gases. Between quantity o f lair and the chimney loss there exists, therefore, at any instant, a definite volume of air which corresponds to a" minimum value of chimney loss and with any chan e from this.

' volume of airveither by way o increase or decrease there results an increase in the chimney loss.

The definitevolume of air corresponding Ito minimum value vof chimney loss varies with the amount offuel, and with the qualmatical illustration of a slightly enlarged scale.

u reversal point 'and C fity of, the fuel and there exists no definite j ply'. T is is illustrated Yiii-the drawing 1y 'for various values of fuel supy-w'herein Fig. .1 is a setof-curves; Fig. 2 is ,-8. diagrammatic view of a system embodying myinventiom and Fig. V3 is a diagram- V detail of Fig. 2 on a Referring to Fig. 1, the line or curve A illustrates the dependence 'of the' chimney loss-V- upon the volume of air L fora delinite loadand nature of fuel andA in connec- ,tionwith curve A it will be noted that there 'isa point 1 which represents the volume for minimum chimney loss value, the chlmney `lossvalue-increasing with either increase or decrease of the quantity of air-from such volume: This point 1 mayrbe termed the particular operating conditions. As the operatlng conditions change, the location of the of the curve and indicates the value of the quantity'ofair to be maintainedvfor minimum chimney loss under theA point corresponding to point 1 changes,

point-s corres onding to other conditions be;

ing those in icated at 2 and 3'on lcurves B These pointsl, 2 and 3 'indicate therefore, values-of air flow to be mainta-ined under different operating conditions iii-order to'` operate with minimum chimney loss 1 Referring now to Fig. 2,5 indicates a reg-- ulating means for regulating the supply of .ueljto ya furnace and 6 indicates a regulatin g means for regulating the supply of air to-.the furnace. These regulating means may L take yany desiredform andare indicated `only If,- on the contrary, the excess of air is too- 4o great, 'it is'known that for its heating there diagrammatically in the drawing. They are` connected b'y stems 7 and 8 to a lever 9,

one end -of which4 i's connected. to the lower "end of 4a threaded rod-10. Stem 7 'l is piv-l I 5 and the air regulating means 6 in the saine ,l

sense, increasing and decreasing both supplies together. Piston 13 and cylinder 14 represent a device movable in accordance with an operating conditionof the furnace for adjusting the fuel and air in accordance with the demand. For example, piston '13 may be subjected to the boiler pressure through a pipe 15, whereby the furnace-will be regulated to .maintain constant boiler pressure.l

Rod 10 is threaded into the hub of a worm wheel 16 supported on a base 16a and it will .be seen that when worm wheel 1611s turned in one direction or the other, rod 10 will be raised or lowered thereby turning .lever 9 on.

fulcrum 11. This it will be seen, adjusts lthe air regulating means 6 but does not move the fuelregulating means- 5. Meshing withv worm wheel 16 is a' worm 17 which is driven by an electric motor 18 ofthe reversing type. Motor 18 is connected by an electric' circuit 19 to a magnetically operated reversing switch- 4 20. In' circuit 19 isa source of electrical energy 21. Motor '18' is a continuously run-v ning motor, and switch 20 serves to reverse the connections tothe motor. to determine.

vthe direction oi rotation. Switch 20` may be of any suitable type. For example, it

may be of the segmental drum and ratchet type which turns always in the same direction and upon each movement reverses the connections on themotor, as indicated at 20,

Fig. 3, the magnetic operating means therefor being indicated at 20".

The magnetic operating means'ot the present example is of the well known ditferen- .tially connected typehaving two sections which balance each other magnetically when energized equally and at the same time, and .either of which will operate the sw1tch when separately energized,

With this arrangment, ifv theswitch has been operated by energizing one section of ,operating means 20band said section is stillj quently energizing the other or the same section so that the switch' will in all cases be advanced to eifecta reversal of motor 18 upon energizing either section or upon energizing 'and deenergizing one section while the other is energized.

This is only one ty e of commonly known magnetically o erate reversing switch, and

as the particu ar type of` switch is not essential to the invention, urther description is believed tobe unnecessary. Connected to 4switch 20 is an operating circuit 22 which contains v.a source of electrical supply 23 and has its terminals connected to two contacts 24 and 25 which togetherv form a circuit closer.- These contacts are in circuit with and controlone section of the magnetic op- 'erating means. y

, The circuit :closer comprisingl 'contacts 24 and'25 -is controlled by means vresponsive to the chimney losses in any suitable manner andV by any suitable means, the arrangementl lbeing such that when the chimney losses exceeda predetermined value, the circuit is closed. Any suitable type of device which measures the chimney'losses or which operatesin response to changes -therein may be utilized. Suitable devices for this purpose may be provided for any particularinstallation and do not per se concern theprescnt invention In the present example, the contact 25 is connected lto the plunger 2 6 ot' a solenoid having a winding 27 in which atiow of current is effectedin accordance with the chimney loss value, or with some determining factor thereof. Current flows continuvously 'through winding 27 and has a certain 'minimum value when the chimney losses are a minmum. When the chimney losses increase the i'low of current increases. lVhen the -flow of current increases due to increase in chimney losses the solenoid plunger 2G is moved upward to bring-contact 25 into engagement with contact 24 thereby closing the circuit on the magnetically operated reversing switch 20. Contact 24 is carried by the movable element 28 of a dash-pot 29. The dash-pot normally holds contact S24-stationary but permits it to. move upward when the pull of the solenoid or its plunger increases.

somewhat, due to increase in chimney losses.

'Upon decrease in 'chimney losses, plunger 26 moves downward away from contact 24 and into engagement with the head which carries contact 2st `'The weight-.of the plunger -is thensui'cient to move Contact 24 downward until a lbalanced position is reached. Contact 24 is thus a oating contact -and can be moved up or down by the movement 'of plunger 26.. Plunger- 26, of course, as-

sumes a position corresponding to the extent to which solenoid `winding 27 is energized. In connection with circuit 22 there is provided also a-time-controlled circuit closer 30. Thisis placed in circuit With the remaining secton' of the magnetic operating means.

The operation is as follows: Motor 18 runs continuously in either one direction or the other thus 'continually increasing or` decreasing the supply of air through the operation lof 'worm Wheel 16. threaded rod' 10, lever 9 and stem 8,;the lever .5l-turning on fulcrum 11. VAssume a load `condition wherein the relation to chimney loss of volume of air is represented by thel l lcurve A which represents Imnimum chimney loss. -The air supply is thus regulated to maintain eflicient operating conditions. c At In connection with'the foregoing, assumethat the contact 24 has just caused o eration of the change-over. switch 20 so -t atthe motor 18 is beingdriven in direction tov diminishthe air supply; in other words, that the point 4 on curve A has just been reached and the circuit closed. Assume further that as a consequence of 4variation of the fuel the' combustion processes no longer take place in accordancevwith characteristic curve A but instead inconformity with the characteristic curve B which has a reversal point located at 2,. To point 4 on curve A there corresponds a point 4n on curve B. A 'comparison of curves A and B indicates that while the quantity 'of air` supplied at point 4 on' curve A represents excess air,the same quantity when supplied on curve-B re resents too little air, It follows, there ore, that since motor 18 has been reversed at point 4 to reduce the air volume, vthe condition exists that, owing to the fact the operation is now taking place according to curve B, the motor will be operating in the wrong direction to move the volume toward'point "2 on curve B. In other words, while according to curve B the motor should be operating in a directionto increasethe air supply,

it is actually operating in a direction to decrease it. As a result, 'the chimney loss measuring device would keep onincreasing and contact 25 would remain closed. Theresult would be'a continual impairment of conditions. In order to avoid an occurrence of this character, the time-controlled reversing switch 30 is provided. This time-control ed reversingswitclr which, as already stated, may beef anyzsuitable type, operates automatically to reverse the direction of rotation of motor 18 at certain definite intervals of time and entirely independently of the position of the magnetically operated reversing switch 20 and the device 26. Asv

a result, even'if conditions set forth occur the time-controlled reversing mechanism will after a predetermined period auto-` matically reverse motor 18 and correct 4the operating conditions.

'As already stated, any-suitable type-fof device for measuring the chimney loss may be utilized to actuate the circuit closer in circuit 22, theessential thing being that the circuit be closed upon the occurrence of chimney losses in excessof a predetermined amount. In the present instance, the rovision of the dash pot in connection wit contact 2.4 effects the result that the circuit closer does not res ond to an absolute quanti- .,t or a definite va ue of the chimney loss but,

ue to the fact that it enables contact 24 to assume different positions, rather to the circumstance that a change inthesense thata'n increase in the quantity lor. chimney loss takes place.

In accordance with the provisions ofthe Patent Statutes, I have described the principle of operation of lmy invention, together with the apparatus which I now' consider to represent the best embodiment thereof, but I desire tohaveit understood that the apparatus shown is only illustrative and that the invention may be -carried out by other means.

What I claim as newl and desire to secure by Letters Patent of the United States, is

1.- In a furnace control apparatus, the combination with means responsivel to the load on the furnace'for automatically regulating the supply of, fuel and air to the furnace, of continuously operating means for' varying the air supply, and means respon-- sive to changes in chimney losses for revers ing the direction of loperation of said continuously operating means.

2'.' In a furnace control apparatus, the combination with means responsive to the load on ,the furnace for automatically regulating the supplyof fuel and vair to the furnace, of continuously operating means 'for varying the air supply, means responsive tochanges in chimney losses for reversing the direction of operation'of said continu,- ously. operating means, and periodically operated time-controlled means for revers-` ing the direction .of operation of said continuously operating means'.

3. In va. furnace control apparatus, the combination with means'responsive to the load on the furnace for automatically regulating the supply offuel and airto the furnace, of continuously operating means for varying theA air supply', a magnetically operated reversing switch for vreversing the di-Vv rection of loperation of said continuously I ,operating means, a circuit closer for effecting operation of said reversing switch, and

means for actuating said circuit closer whenever the chimney losses depart from a predetermined value.

4. In a: furnace Acontrol apparatus, the

combination with means responsive to the yload on the furnace for automatically regulating the supply of fuel and air. to thefurnace, of continuously operating means for varying the air-supp y, a magnetically operated reversing switch 'for reversing 'the direction 'of operation of said continuously "operating means, a circuit closer for effect` thereto, continuously operating` means for sponsive toI changes in chimney losses for 10 regulating said controlling means, and reversingthe direction of operation of said means responsive to changes in chimney continuously operating means, and periodlosses for reversing the direction of operically operated time-controlled means for ation of 'said continuously operating means. reversing the direction of operation of said 6. The combination with a furnace, of continuously'operating means. means for controlling the supply of ail" In witness whereof, I have hereunto set thereto, continuously operating means for my hand this 22nd' of January 1925. regulating said controlling means, means re- EODOR STEIN. 

